Fires in sites that are partially or totally confined are extremely difficult to contain much less to extinguish due to a number of factors among which are included, but not limited to, factors such as heat buildup, the ready availability of fuel and the presence of toxic gases, all of which make delivery of fire suppressant material and extinguishing of the fire very difficult. Confined areas include locations such as structures, storage tanks, subway and highway tunnels and underground mines as well as other types of below surface fires, such as landfill fires for example. These sites can combine the worst dangers to property and life in that the hot combustion gases are confined and can be prone to explosion and can provide additional fuel to the fire. In addition the combustion gases normally contain toxic levels of carbon monoxide gas, methane gas and other toxic substances. In coal mine fires, for example, the abundance of fuel in a confined, poorly accessible area practically guarantees that the fire will burn for extremely long periods of time with resultant loss of production and substantial property loss. Many coal mines must be abandoned in the event of a fire because of the great difficulty in extinguishing the fire. For example the Jonesville coal mine fire started more than 30 years ago and is still burning. The town of Centrala, Pa. has been abandoned because of a coal mine fire that began in 1961 because of the seeping of noxious gases to the surface. The residents of the City of Youngstown, Pa. have seen their priority values drop to near zero and they are concerned that they will lose their homes due to the Percy mine fire in Fayette County, Pennsylvania that has been burning for more than 30 years.
Although not necessarily prone to the extremely long burning periods encountered in coal mine fires, other fire locations such as underground fuel storage tanks, above ground chemical storage tanks and the like present similar problems in extinguishing fires occurring therein. It is difficult to apply fire suppressant material to the fire because of the location of the fire in a confined area and the resultant danger to the fire firefighters from explosion, heat buildup and toxic gases.
The usual fire suppressant material utilized in the fires even for fire in confined areas is water. However, water is quickly vaporized at the high temperatures encountered in confined areas engulfed in fire and relatively ineffective in extinguishing such fires. Furthermore, areas of active burning and/or high surface temperatures that can result in ignition can occur on the sides or upper surfaces of a confined area. These areas must be contacted with fire extinguishing material in order to smother the fire and to reduce the surface temperature. Liquid fire extinguishing materials are effective only for the lower surface of a confined area, unless the area is completely filled with the liquid. In most situations, this is impractical, if not impossible, and highly expensive. Air expanded foam has been suggested as a fire suppression material for a confined areas. However, air expanded foam actually supplies additional fuel, oxygen, to the fire which, as it is consumed, results in a breakdown of the foam so that the foam does not have the smothering properties necessary for effective fire extinguishing. Accordingly, foam has not generally been accepted as a suitable fire extinguishing material for fires in confined areas. The latest concept uses a jet engine thrust of water vapors and inert gases into a mine to smother the fire. This requires months of preparation, including the development of a mounting structure to support the jet when subjected to the engine load on thrust dynamics. Moreover, a new mounting structure would have to be designed for each mine that would appear to be cost prohibitive.
Therefore, a need exists to address the aforementioned deficiencies and inadequacies.